1. Field of the Invention
The present invention relates to a jack assembly, and more particularly to a jack assembly, which can be operated electrically or manually.
2. Description of the Related Art
A conventional jack assembly (50) in accordance with the prior art shown in FIG. 4 comprises two lower arms (52) each having an upper end portion and a lower end portion pivotally attached to a base (51), two upper arms (520) each having an upper end portion pivotally mounted to a support bracket (54) and a lower end portion pivotally mounted to the upper end portion of one of the two lower arms (52), and a drive shaft (55) rotatably mounted between the lower arms (52) and the upper arms (520), and having a first end portion (57) in which a rod (58) is inserted to rotate the drive shaft (55), and a second end portion formed with an outer thread (56) and rotatably mounted in an elbow (53). The elbow (53) is mounted to the lower arm (52) and the upper arm (520), and has an inner thread (not shown) mating with the outer thread (56) of the drive shaft (55) such that the elbow (53) displaces relative to the drive shaft (55) when the drive shaft (55) is rotated.
In operation, the rod (58) can be rotated so as to rotate the drive shaft (55) whose rotation causes the elbow (53) to displace such that each of the two upper arms (520) is pivoted relative to the respective lower arm (52), thereby lifting the support bracket (54) which can be used to lift an object such as the chassis of a car so as to inspect the chassis for maintenance of the car or to replace an tire of the car. In such a manner, the jack assembly (50) is operated manually. However, it requires a great deal of time and effort to operate the jack assembly (50) manually, thereby causing inconvenience to the user.
A second conventional jack assembly (60) in accordance with the prior art shown in FIG. 5 comprises two lower arms (62) each having an upper end portion and a lower end portion pivotally attached to a base (61), two upper arms (620) each having an upper end portion pivotally mounted to a support bracket (64) and a lower end portion pivotally mounted to the upper end portion of one of the two lower arms (62), and a drive shaft (65) rotatably mounted between the lower arms (62) and the upper arms (620), and having a first end portion to which an electric drive (66) is attached to rotate the drive shaft (65), and a second end portion formed with an outer thread (not shown) and rotatably mounted in an elbow (63). The elbow (63) is mounted to the lower arm (62) and the upper arm (620), and has an inner thread (not shown) mating with the outer thread of the drive shaft (65) such that the elbow (63) displaces relative to the drive shaft (65) when the drive shaft (65) is rotated.
In operation, the electric drive (66) includes a plug (67) which can be inserted into a receptacle (not shown) of the power supply (not shown) of a car so as to operate the electric drive (66) which rotates the drive shaft (65) whose rotation causes the elbow (63) to displace such that each of the two upper arms (620) is pivoted relative to the respective lower arm (62), thereby lifting the support bracket (64) which can be used to lift the chassis so as to inspect the chassis for maintenance of the car or to replace a tire of the car. In such a manner, the jack assembly (60) is operated electrically. However, the electric drive (66) stops its operation when the power supply is dead due to the car failing such that the jack assembly (60) cannot be operated, thereby limiting the versatility of the jack assembly (60). In addition, the electric drive (66) secured on the upper arms (620) cannot be removed therefrom.
The present invention has arisen to mitigate and/or obviate the disadvantage of the conventional jack assembly.